Wow. Just think, I didn't even know what QR codes were a few weeks ago. I really see them blooming in the next few years (Ha!Bloomberg/ Blooming!). I scanned one from a Meijers grocery coupon and got a 10 second commercial sent back to me.
Very progressive! Excellent use for that specific labeling technology --- especially in a high density population area where a construction project could be a big hassle. This would make it easy for the public passerby to find out more about it, and perhaps a target completion date. Plus, you are certain the contractor has a legal permit from the city of New York for the work they are doing.
UNICEF is playing with the idea of using QR Codes to encouraging people to donate items on a 1X2 (buy one, give one) basis while shopping at the store. It is a pretty neat way to utilize the technology, and encourage people to donate.